Compounds of formula (I) and pharmaceutically acceptable salts, esters, amides, or radiolabelled forms thereof, wherein R1, Z1, Z2, and n are as defined in the specification, are useful in treating conditions or disorders prevented by or ameliorated by Tropomysin receptor kinases (Trk). Methods for making the compounds are disclosed. Also disclosed are pharmaceutical compositions of compounds of formula (I), and methods for using such compounds and compositions.